SQL Query check if unique constraint is Updated , If its not Altered then run Alter Query

Question

I need a IF Statement to check and run SQL Query

  alter table [ReportableResults] add constraint   
   Unique_ReportableResults_ReportableResultCode_IsCalculated unique (ReportableResultCode, IsCalculated);  

Above Code is Working Fine.....But I dont want to run Everytime...

I want to check if its already altered then not need to run the Above Query.

Answer 1

The following code will create the constraint if there is no object named Unique_ReportableResults_ReportableResultCode_IsCalculated, but if it already exists, the code will do nothing.

If Not Exists(Select * From sys.objects Where Name = 'Unique_ReportableResults_ReportableResultCode_IsCalculated')
  alter table [ReportableResults] add constraint
   Unique_ReportableResults_ReportableResultCode_IsCalculated unique (ReportableResultCode, IsCalculated);

Tom